Pieces of machinery, especially turbines and compressors as well as their drives, are increasingly equipped with complex digital controls and regulators.
Modern digital regulators and controls make it possible, on the one hand, to determine the specific load of the machine more accurately at the given operating point by the use of complex calculation methods and to load the machine components higher as a result, without reducing the service life of the entire piece of machinery. On the other hand, using complex control and regulation algorithms, an automatic protection of the piece of machinery can be achieved even against incidents which were uncontrollable before.
As the complexity of the regulation and control algorithms increases, the start-up of such pieces of machinery also requires a comprehensive knowledge of the system.
Compressors and turbines are used worldwide, frequently in very remote areas, e.g., in gas compressor stations along natural gas pipelines, on oil drilling platforms, but also in chemical or petrochemical plants.
To start up a compressor or turbine, it is necessary to optimize control parameters, and the piece of machinery is operated together with the upstream and downstream process. The control parameters are to be set at the time of this first operation of the complete unit such that the control circuits will respond to changes in the set point and the actual value as quickly as possible, but they nevertheless display a stable behavior in the entire working range. This optimization can be performed only at the site of installation during the operation of the entire unit.
Furthermore, limit values for hazardous states are to be determined and parameters are to be correspondingly adjusted within the regulation and control at the time of the first start-up or at the time of a start-up after shutdowns.
Modern machine monitoring systems make it possible to represent the current working point of the machine dynamically in a characteristic diagram. Such characteristic diagrams may represent, e.g., the difference in enthalpy as a function of the volume flow, but also the efficiency or the power generated or consumed as a function of the flow. The dynamic display of the current working point in the characteristic diagram enables the operating personnel to evaluate the operating performance as well as the operating reserves available. Other representations provide information on, e.g., soiling conditions, etc.
The characteristic diagrams of the machines are usually calculated theoretically and are programmed in the machine-monitoring unit before the piece of machinery is shipped. However, the characteristic diagram measured after the completion of the piece of machinery may deviate from the theoretically calculated one because of manufacturing tolerances.
The characteristic diagram is therefore usually measured during the start-up and is compared with the calculated characteristic diagram. In the case of deviations, the parameters are to be changed in the program of the machine-monitoring unit such that the characteristic diagram represented will correspond to the measured characteristic diagram.
The characteristic diagram of the piece of machinery may change after a relatively long operating time either due to changes within the plant, e.g., due to changes in the pipeline routing, but also due to wear or contamination of the piece of machinery. Adjustment of the characteristic diagrams being stored or of the calculation algorithms is necessary in these cases to determine the characteristic diagrams or their parameters from time to time.
Modern digital controllers and controls make it possible to change over algorithms and control sequences by making changes in the software, without any changes being necessary in the hardware. It is thus possible to regularly update regulation and control algorithms to the latest technical development at low cost.
All the above-mentioned changes make it necessary for experts to be present on the site, who can analyze the measured data and can determine from them the values to which the parameters are to be set or how the algorithms are to be changed and how the corresponding changes are to be made in the program.
The sending of experts to the remote operating sites is often associated with high costs. In the case of sudden breakdowns, a software expert has to travel to the plant to analyze the operating parameters measured and recorded on the site and to infer the cause of the disturbance from them. To avoid further incidents, it is often necessary to make changes in the software. These changes are to be made and tested by the expert on the site.
Hours or even days frequently pass before an expert arrives at the plant. The plant is not ready to operate during this time. The cost due to the loss of production is often considerable.
Transmission processes which make possible the transmission of measured values from any site to another site via long-distance data line have been known for a long time. These make it possible for an expert to obtain information on the operating state of a machine or plant from another site and to analyze that information at his usual place of work. He can then give recommendations to another expert present at the site to change parameters or program structures, which the expert present at the plant can implement. The need for an expert to be present at the site cannot be eliminated in this process.
Transmission processes have also been known, which make possible the transmission of computer programs from any site to another site via long-distance data line. However, these processes do not accomplish the object according to the present invention, because the program transmitted via the long-distance data line must be loaded into the regulation and control system on the site via a programming device and it must be started. These activities also make necessary the presence of a systems specialist at the site.
A programming device is usually connected locally to the control and regulating system to start up a piece of machinery. The programming devices are permanently installed in some controls and regulations, e.g., in a system according to EP 0 378 713. A change that needs to be performed in the program for the control and regulating system is performed such that the complete program is loaded into the programming device, and the change is performed in the programming device. The changed program is then loaded in full length into the memory of the control and regulating system. The entire program, which is frequently rather comprehensive, must be reloaded even if only one line of the program is changed. This requires high-speed data transmission, which is possible with broad-band data lines only. The programming device must therefore be located in the vicinity of the control and regulating system at the time of the start-up. Remote programming is not worthwhile because of the high cost of transmission with broad-band data lines, and frequently it is also technically unfeasible.
Immediate feedback of the effect of a change in parameters, structures or program on the process is frequently indispensable at the time of start-up. The expert must have a possibility of immediately intervening with the control and regulating system, and he also must be able to perform control commands, should the change made in the parameters, structures or programs lead to an unacceptable or even hazardous mode of operation of the machine or plant. This also requires broad-band data lines from the piece of machinery to the programmer.